How to get VM arguments from inside of Java application

Question

I need to check if some option that can be passed to JVM is explicitly set or has its default value   To be more specific  I need to create one specific thread with higher native stack size than the default one  but in case the user wants to take care of such things by himself by specifying the -Xss option I want to create all threads with default stack size  which will be specified by user in -Xss option    I ve checked classes like java lang System and java lang Runtime  but these aren t giving me any useful information about VM arguments   Is there any way to get the information I need

User · Answer

I haven t tried specifically getting the VM settings  but there is a wealth of information in the JMX utilities specifically the MXBean utilities  This would be where I would start  Hopefully you find something there to help you   The sun website has a bunch on the technology   http   java sun com javase 6 docs technotes guides management mxbeans html

User · Answer

With this code you can get the JVM arguments   import java lang management ManagementFactory  import java lang management RuntimeMXBean      RuntimeMXBean runtimeMxBean   ManagementFactory getRuntimeMXBean    List lt String gt  arguments   runtimeMxBean getInputArguments

User · Answer

At startup pass this -Dname value  and then in your code you should use  value System getProperty  name      to get that value

User · Answer

I found that HotSpot lists all the VM arguments in the management bean except for -client and -server  Thus  if you infer the -client -server argument from the VM name and add this to the runtime management bean s list  you get the full list of arguments   Here s the SSCCE   import java util    import java lang management ManagementFactory   class main     public static void main final String   args        System out println fullVMArguments            static String fullVMArguments         String name   javaVmName        return  contains name   Server      -server           contains name   Client      -client                 joinWithSpace vmArguments            static List lt String gt  vmArguments         return ManagementFactory getRuntimeMXBean   getInputArguments           static boolean contains String s  String b        return s    null  amp  amp  s indexOf b   gt   0         static String javaVmName         return System getProperty  java vm name           static String joinWithSpace Collection lt String gt  c        return join      c          public static String join String glue  Iterable lt String gt  strings        if  strings    null  return         StringBuilder buf   new StringBuilder        Iterator lt String gt  i   strings iterator        if  i hasNext            buf append i next           while  i hasNext            buf append glue  append i next               return buf toString            Could be made shorter if you want the arguments in a List lt String gt    Final note  We might also want to extend this to handle the rare case of having spaces within command line arguments

User · Answer

If you want the entire command line of your java process  you can use  JvmArguments java  uses a combination of JNA    proc to cover most unix implementations

[java] How to get VM arguments from inside of Java application?

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